Process of obtaining fibers from bagasse



-Patented July 22, 1924.

UNITED mm Parism .orr ca.

JOHN R. SHAW, or MINNEAPOLIS, MINNESOTA.

raoonss or OBTAINING FIBERS rRoM'BAGAssE.

No Drawing. Application filed October 23, 1920, Serial fio. 419,046. Renewed J'anuary20, 1923.

State of Minnesota, have invented certain new and useful Improvements in Processes of Obtaining Fibers from Bagasse; and. I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to a' process for treating bagasse and analogous fibers and has for its object to provide a method which will produce both wall board making fibers as well as papermakingfibers from bagassc and analogous raw material at a minimum of cost.

combinations of steps constituting the process all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that the precise invention may be the more clearly understood it is said In my copending application Sr. No. 419,-

044. filed, Oct. 23, 1920, and entitledP'rocess" ing, but insufiicient to dissolve out their natural pith. By this procedure, the bagasse fibers are obtained in an unusually resilient and strong condition, for making wall boards, while their natural pith which is not destroyed is found to be a very efficient heat insulator and to add very materially to the yield of board making substance.

By the term encrusting casings found in the description and claims is meant what appears to be a more or less stiff and brittle fibrous casing to which the relatively flexible and strong fibers are found to be at.- tached when dry bagasse is observed under a magnifying glass. I believe the fibers of this casingare made up of those formin the outer skin, or wall, of the stalk, and

are substantiall free from pith-cells, while the said more exible fibers arelfound farther inside the stalk and are associated with numerous pith cells. Whatever may be the true nature of this so called casing, it is a fact that it constitutes a brittle mass which, when mechanically removed, frees the more flexible fibers and renders them suitable for i and they have also injured to a greater or less extent the strength of the ultimate fibers all as is set forth in said copending I application.

In carrying out this invention, on the other hand, I first proceed to only partially ,cook the bag'asse and analogous fibers in With these and other objects in view theinvention consists in the novel steps and the same-manner as is disclosed in said copendin'g application. That is, I subject said-fibers to any suitable chemical such as an alkali, a sulphate, or a sulphite, and cook the same only so long as is necessary to loosen u theencrusting casing of said fibers and am careful not to prolong the cooking sufficiently to dissolve out a substantial portion of the valuable natural pith with which said fibers are accompanied. I thus not only use up a minimum quantity of chemicals but I preserve the valuable wall board making pith.

After the bagasse and analogous fibers have been thus only partially cooked, I subject the same .to the actionof a suitable beating engine, whereupon Icrecover a portion of the longer partially cooked fibers with their natural pith and mechanically separate this said portion from the shorter fibers also accompanled by their natural pith.

. The shorter fibers wh1ch-are not sepa-' rated from the natural pith are used for board making purposes precisely as is dis,;.

closed in my said copending application above mentioned, but may also have added thereto the dissolved cellulosic constituents and pith ofsaid longer fibers as will presently appear. The first mentioned portion of fibers, however, which also has not as yet been separated'from its natural pith, I further cook in any suitable chemical solution to,

such an extent as will'dissolve said pith and form paper making fibers therefrom.

, These said fullycooked fibersv are found to make a very high grade pulp from which a superior grade of paper can be manufactured. It will now be clear that by following the procedure above outlined, I avoid dissolving a large portion of the pith in treating bagasse fibers, and therefore avoid the great loss of cellulosic material that has been heretofore experienced by practicing othercooking processes and by saving this pith with the board making fibers, all loss of the same is avoided because the mechanical sepa;

ration of the two classes of fibers saves not only the pith but a considerable amount of the short fibers which are valuable for the manufacture of said heat insulating wall boards.

While it is true that some of the cellulose material of the long fibers will be lost during the second cooking, yet, this loss does not amount to anythinglike the total loss that is experienced in the prior processes, whether the pith is mechanically stripped from the fibers before the cooking, or is completely dissolved therefrom during the cooking. I

It is found in practice that it takes a less weight of chemicals to makea ton of paper making pulp by this process than by the prior processes, and the said valuable board making material is obtained in addition as a by product. I

It is obvious that those skilled in the art may vary the details of the procedure without departing from the spirit of the same, and

therefore, it is not desired to be limited to mamas the above disclosure except as may be required by the claims.

What is claimed is: a

1. The process of treating bagasse and analogous fibers which consists in cooking said fibers with their natural pith sufficiently to loosen their encrusting casings but insufiiciently to dissolve a substantial; portion of said pith; subjecting said fibers to the action of a beating englne; separating out a tion of a beating engine; separating out a portion of the. long fibers from the short fibers present after leaving said engine; subjecting said portion of long fibers to a second cooking action to produce a paper making pulp; and a solution of the pith accompanying said long fibers; recovering said short fibers; forming the same into a board;

and applying thereto said solution, substantially as described a y In testimony whereof I afiix my signature;

JOHN K. straw; 

